Get up and work out, or stay in bed a bit longer? Work out, or sleep? Work out, or sleep? It's the eternal dilemma. You want to stay curled up under your blanket for an extra hour, but you know it'll be tainted later by the guilt of forgoing a gym session.

It turns out you shouldn't feel guilty about staying in bed at all. According to the experts, getting enough sleep can be just as beneficial for your health and your weight as going to the gym can be.

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All in the hormones

Dr. Guy Meadows, who's been working with Philips on their new Somneo Sleep and Wake-up Light, points out that not getting enough sleep each night actually has a link to having a higher body fat percentage.

"Sleeping less than 7-8 hours per night is linked to higher percent body fat. Research suggests that people who average 6 hours per night are 27% more likely to be overweight," he says. "Those who average 5 hours per night are 73% more likely to be overweight," the doctor adds.

And it's all to do with hormones - two in particular. "Ghrelin regulates our appetite and so how hungry we feel, whereas Leptin regulates the feeling of fullness, the cue to stop eating," explains Dr. Meadows.

"Research demonstrates that after a poor night of sleep Ghrelin levels increase and Leptin levels decrease, meaning we feeling more hungry and yet less full, hence why we tend to eat more."

Poor decisions

According to research, after a poor night of sleep we experience a heightened desire to eat - by up to 45% more than normal levels - and the food choices we make the next day are scientifically proven to be much worse.

"Research suggests that poor sleep causes us to choose higher calorific food. Scientists from Uppsala University in Sweden demonstrated that sleep deprived individuals select foods that are on average 9% higher in calories than when in a rested state," says Dr. Meadows. It's thought this is down to either a reduction in willpower or an increase impulsive decision making.

And nutritionist Lily Soutter agrees with Dr. Meadows that sleep can actually be just as valuable to your health and fitness than a session at the gym. She references a recent study that discovered lack of sleep can increase belly fat - which is notoriously hard to shift.

"Scientists have analyzed levels of the stress hormone cortisol in sleep-deprived subjects. They found elevated levels of cortisol after a sleepless night, which was especially high between the hours of 4-9pm. High cortisol can signal for fat to be store around the middle," she says.

Ineffective workouts

Soutter also points out that if you don't get enough sleep, your workouts will be significantly less effective anyway - so perhaps you're better off getting some extra shut-eye. "During sleep, muscle tissue repairs and new cells are regenerated, therefore sleep deprivation is the enemy of building that all-important fat burning muscle mass," the nutritionist says.

Dr. Meadows thinks the same. He explains that continuously low levels of sleep can have the same negative impact on cognitive performance as two whole nights without sleep. "This means that being focused and attentive, reaction time and your ability to assess risk are seriously impaired. Exercising [when] tired therefore increases your risk of having an accident and potentially injuring yourself," he explains.

"If you are serious about staying healthy and keeping fit, you are much better off making sleep a priority in your life."